U.S. Pat. No. 3,956,000 discloses the preparation of low molecular weight fluorocarbon polymer, referred to as wax in the patent, by direct polymerization, including copolymerization, of one or more monomers, at least one of which is a fluorocarbon monomer. Because the polymerization is carried to low molecular weight in the presence of a chain transfer agent, the polymerization is called telomerization. The low molecular weight fluorocarbon polymer is made in an aqueous dispersion polymerization system using initiators and emulsifiers known and generally used for homopolymerization of tetrafluoroethylene in aqueous dispersion. The initiators disclosed are those consisting of a plurality of compounds to form a redox system, notably ammonium persulfate/sodium bisulfite such as used in the telomerization process of the Examples of the patent. The low molecular weight polymer is then isolated from the dispersion and obtained as a powder.
A principal utility of directly polymerized low molecular weight fluorocarbon polymer such as described above is in combination with thermally stable, high melting essentially non-fluorocarbon polymer to form a coating composition from a liquid medium onto the surface of clean metal sheet typically supplied in the form of a roll or coil thereof. The coating is dried and then baked to fuse the coating, wherein the non-fluorocarbon polymer forms a wear surface on the surface of the metal sheet, and the fluorocarbon polymer provides release properties to the coating, making articles fabricated from the sheet useful in such applications as bakeware. This fabrication normally is carried out by stamping out shapes from the sheet, followed by forming these shapes into the article desired, such as by bending and/or folding. Unfortunately, the rigorous treatment of the coated sheet to obtain the desired fabricated articles therefrom causes a waxy buildup on the fabrication equipment, which comes from the coating on the metal sheet. Periodically, the fabrication operation must be stopped for cleaning of the fabrication equipment to remove the waxy buildup.